The main goal of this proposal (Project 6 of 11 of a U54 Consortium grant entitled, "SysCODE: Systemsbased Consortium for Organ Design and Engineering") is to define engineering principles and microstructural design criteria that when combined with the molecular blueprint uncovered by this Consortium will permit us to fabricate biomimetic materials with appropriate mechanical and chemical signals necessary to induce organ regeneration. We will define how micromechanical forces generated by tissue cells and resisted by extracellular matrices (ECMs) with different mechanical compliance and internal microstructure contribute locally to the regional tissue shape transformations and progressive structural remodeling that mediate morphogenesis and hierarchical self assembly of complex organs. The long term goal is to use the physical design criteria identified in this effort to fabricate multifunctional biomimetic scaffolds that can reprogram stem cells to recapitulate organ formation. These scaffolds will mimic the micromechanical features of living ECMs that control cell fate switching locally, and will spatially orient chemical and adhesive signals that. trigger appropriate developmental cascades. To identify fundamental design principles, we will break down this hierarchical self assembly process into individual steps or critical "morphogenetic modules" ,(e.g., mesenchyme condensation, epithelial budding and folding, cell fate switching, and epithelial-mesenchymal transitions) that underlie epithelial-mesenchymal interactions during development of the tooth, as well as pancreatic islets and heart valves. Relevant molecular regulators and high throughput ECM fabrication strategies will be accessed through collaboration with other members of this Consortium. The new information, ECM materials and design criteria discovered in this proposal will then be integrated with the other projects to develop prototype materials for tissue and organ engineering. The specific aims include: 1) To analyze how cell-generated contractile forces and ECM micromechanics vary spatially during morphogenetic shape transformations in the developing tooth, 2) To determine the effects of altering endogenous cell-generated tensional forces or applying external mechanical loads on tooth development, and 3) To determine the effects of varying the mechanics, structure and chemistry of artificial ECMs on morphogenesis and cell fate switching in tooth, pancreatic islet and heart valve.